Deflection system for cathode-ray tubes



Nov. 15, 1949 H. w. LEIGHTON DEFLECTION SYSTEM FOR CATHODE-RAY TUBES 3Sheets-Sheet 1 Filed Oct. 30, 1946 JNvmwan Nov. 15, 1949 H. w. LEIGHTON2,488,132

DEFLECTION SYSTEM FOR CATHODE-RAY TUBES Filed Oct. 30, 1946 3Sheets-Sheet 3 |llll llllllll we? IZILJIIII all H r1 i M .15 M1 Ilfivewrofi Patented Nov. 15, 1949 DEFLECTION SYSTEM FOR" CATHODE-RAYTUBES Herndon Wheeler Leighton, Hackensaok, N. J assignor to Allen B. duMont Laboratories, Inc., Passaic, N. J., a corporation of DelawareApplication October 30, 1946, Serial No. 706,727

6 Claims.

This invention relates to a cathode-ray tube and more particularly tothe deflection system thereof.

In accordance with this invention provision is made for connectingcoaxial cables to deflection plates of cathode ray tubes and theseplates are so shielded that very high frequencies can be applied to themwith .a minimum of interference from outside sources. Also, theinductance of the circuit is kept low and capacitances betweenelectrodes of the tube are minimized.

In carrying out the invention, provision is made so that the outerconductors of coaxial cables. can be attached to threaded connectorsthat are made up of several pieces that pass through the wall of theneck of the tube. The length of the conductors inside oithe neck is veryshort due to the fact that the conductors enter the neck radially.

A shield is provided inside of the neck of the tube around thedeflection plates to protect them.

from external interference and another shield is provided to separatethe horizontal from the vertical deflection plates to prevent the twofields from interacting or influencing each other.

The invention maybe understood from the description in connection withthe accompanying drawings, in which:

Fig. 1 is a longitudinal section through the neck of the tube partlybroken away.

Fig. 2 is a perspective view of the rings that hold the deflectionplates and their connectors in position.

Fig. 3 is a perspective view of one of the outer coaxial connectorbushings.

Fig. 4 is a plan view of the deflection plate assembly and,

Fig. 5 is a side View of the deflection plate assembly partly along thesection 5-5 of Fig. 4.

Fig. 6 is a plan view of a modified form of the deflection plateassembly shown as a section across the neck of the tube to show how theassembly is mounted.

Fig. 7 is a longitudinal section through the neck of the tube, as shownin Fig. 6, partly broken away.

In the drawings, reference character I indicates a portion of the neckof a cathode-ray tube through the walls of which four coaxial connectorsextend. A portion 2 of each coaxial assembly is anchored in the neck Iand makes contact with the outer coaxial connector bushing 3 that isheld in place by the seals consisting of a corn plaster shaped piece ofceramic 4 and cement 5.

The bushing 3 which is externally threaded to receive the outer lead ofthe coaxial cable has .s

strucksout tabs 3a to form a tight fit in the tubular connector 2. Thisbushing is flanged at..3.' to hold its position againstthe neck of thetube I. Each one. of these bushings is inserted into a connector 2 andis cemented to the glass neck I by seals it and 5.

The inner end of portion 2 fits into a connecto cable. This slit portionis supported by the ring of insulating material 9 and is spot welded atII to the deflection plate-lead I2. which supports the deflection plateI3.

Metal rings I4 and I5 (Figs. 1 and 2) are pro vided with grooves I4 andI5 and are clamped together by bolts I6- and nuts lfi' to hold theserings on the connectors 6. These connectors B are cemented to the rings14 and I5 as indicated Electrostatic shields I1 and I 8 that haveflanges I? and I8 are bolted onto the deflectionplate assembly by nu.sIS on the bolts I6. A disc shaped shield I9 (Fig. 5) having a centralhole- It for the electron beam is clamped between the discs I4 and I5.

In the final assembly of the tube the deflection plate sub-assembly asshown in Figs. 4 and 5'may be attached to the electron gun structure,not

shown. The stem carrying the electron gun structure and the deflectionplate assembly is then inserted in the neck of the tube and adjusteduntil the deflection plates are at the proper distance from the screenof the tube. The stem is then sealed in place. Each of the flangedportions 2 of the deflection plate assembly will then be in closeproximity to the inside wall of the neck I of the tube. The glass of theneck I is then heated and pushed down around the flanged portions 2 soas to complete a vacuum tight seal at this point. Holes are then meltedthrough the glass over these flanged portions 2 permitting theconnectors 3 to be inserted so as to give good electrical contactbetween them, with the flange 3 resting on the seal between the neck andthe curved portion of 2. The corn plaster shaped seals 4 are then put inplace over flange 3' and affixed with cement 5 so as to hold flange 3'firmly in place with respect to the curved portion 2 to complete theoperation.

Figs. 6 and '7 show a modification of the deflec- 3 tion plate assemblyand the way it is mounted in the neck of the tube.

As shown in these figs. the part 20 corresponding to part 2 of the otherfigs. does not have the curved flange shown in Figs. 1, 4 and 5 at thepoint where it fits into the glass. It goes straight through and athreaded and flanged piece 2| fits over it and receives the outercoaxial connector on its threads.

In this modification, a conductor 22 connects the inner conductor of thecoaxial line with the connector [0 attached to connector II thatsupports the deflection plate I 3. It is supported along the axis of theouter connector 20 by a bead 23 of glass which provides a vacuum tightseal.

The deflection plate lead assembly shown in Figs. 6 and 7 is held inposition by threaded metal pieces 24 and 25 which fit each other and thesleeve 20 and are so arranged as to make good electrical contact betweenthe parts 20 and 26.

The transverse shield 21 of the deflection plate I3 is constructed witha recess 28 to receive the deflection plate connectors.

In the final assembly according to Figs. 6 and 7 the deflection plateassembly without the bushing 2| is inserted into the tube neck. Afterlocating the deflection plate assembly the tube neck is heated andsealed about the four connectors 20 to the tube body. The bushings 2|are then slipped over the protruding portions of the sleeves 20 and aresealed in place as before with the cornplaster shaped seals 4 and thecement 5.

What is claimed is:

1. In a cathode-ray tube having deflection plates, a metal shield forsaid plates, means to connect the inner conductor of a coaxial cable toeach of said plates through said shield and means to attach the outerconductor of said cable to said shield.

2. The device of claim 1 in which the last mentioned means of attachmentof the outer conductor of said cable to the shield comprises a tubularmember with one end set in the shield and the other set in the glassneck of the tube and protruding from it with this protruding portionadapted to receive the outer conductor of the coaxial cable.

3. The device of claim I in which the last mentioned means of attachmentof the outer conductor of said cable to the shield comprises a tubular 4member with one end set in the shield and the other having a recurvedflange and set in the glass neck of the tube and a bushing having itsouter portion adapted to receive the outer conductor of a coaxial cableinserted into the flanged portion of the tubular member.

4. In a cathode-ray tube, a plurality of coaxial lines passing throughthe wall of the neck of said tube and each having its outer conductorhermetically sealed in said wall and a shield for deflection plates insaid tube to which the outer conductor of each of said cables isattached.

5. In a cathode ray tube having two pairs of deflection plates, acylindrically shaped metal shield for said plates, means to connect theinner conductor of a coaxial cable to each of said plates through saidshield and means to attach the outer conductor of said cable to saidshield, and comprising two pairs of semi-cylindrical metallic membersattached to said shield and extending inwardly therefrom formingcomplementary shielding channels for conductors leading to said plates.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,753,317 Rothen Apr. 8, 19301,937,849 Slack Dec. 5, 1933 2,245,581 Ekstrand June 17, 1941 2,268,194Glass Dec. 30, 1941 2,360,660 Eaton et al. Oct. 17, 1944 2,404,085Okress et al July 16, 1946 FOREIGN PATENTS Number Country Date 479,961Great Britain Feb. 15, 1938

